1. Field of the Invention
The present invention relates to antenna systems. More specifically, the present invention relates to antenna systems mounted on glass windshields of vehicles.
2. Description of the Related Art
Antennas are required for virtually every wireless communication application including radio, cellular, and global positioning system (GPS) applications. Many such applications involve the use of transmitters and/or receivers mounted in vehicles. For these applications, glass mounted antennas are often used. Typically, the antenna is electrically connected to a coupling mechanism which is secured to an outside surface of the windshield of the vehicle. On the opposite side of the windshield, a second coupling device couples radio frequency energy from the antenna to the transmitter or receiver via a cable.
Unfortunately, a coupling loss is typically experienced with conventional glass mount antenna arrangements. At 800 MHz, the coupling loss may be as much as 3 decibels. At higher frequencies, the coupling loss increases substantially. Consequently, for certain high frequency applications, such as satellite radio (at 2.4 GHz), the coupling loss is expected to be unacceptably high (2-4 dB).
As these losses would make reception difficult, a need exists in the art for a system or technique for reducing the losses associated with glass mounted vehicle antennas for high frequency wireless communication applications, particularly satellite radio applications.